Hot water heaters and other pressure vessels typically have a relief valve that opens to expel fluid when a temperature or pressure within the water heater exceeds predetermined levels. In this manner, explosions can be prevented by reducing the volume of fluid in the water heater, which reduces the temperature and pressure within the water heater. However, the relief valves often develop calcium, limestone and other mineral deposits over time that can cause the relief valves to fail.
To prevent hot water heaters from exploding when the relief valve fails to open, it is known to monitor a temperature or pressure of the water heater. Exemplary devices are discussed in U.S. Pat. No. 6,766,835 issued in July 2004, and U.S. Utility application with Ser. No. 12/391,018 filed on Feb. 23, 2009. By monitoring the temperature or pressure of the water heater, energy to the water heater can be restricted prior to the temperature or pressure of the water heater becoming critical. However, such monitors fail to detect a situation in which the relief valve is stuck in an open position, which can lead to flooding and wasting a large amount of water and energy before the problem is detected. This is especially problematic since many relief valves expel water out of the sight of users, which increases the difficulty of manually detecting a failed valve.
Thus, there is still a need for a system that monitors a relief valve of a water heater or other pressure vessel, and restricts an energy or water flow to the water heater when the relief valve is stuck in an open position.